Diketopyrrolopyrrole polymers for use in organic field effect transistors

ABSTRACT

The present invention relates to polymers comprising a repeating unit of the formula I, or III and their use as organic semiconductor in organic devices, especially an organic field effect transistor (OFET), or a device containing a diode and/or an organic field effect transistor. The polymers according to the invention have excellent solubility in organic solvents and excellent film-forming properties. In addition, high efficiency of energy conversion, excellent field-effect mobility, good on/off current ratios and/or excellent stability can be observed, when the polymers according to the invention are used in organic field effect transistors.

The present invention relates to polymers comprising a repeating unit ofthe formula I, or III and their use as organic semiconductor in organicdevices, especially an organic field effect transistor (OFET), or adevice containing a diode and/or an organic field effect transistor. Thepolymers according to the invention have excellent solubility in organicsolvents and excellent film-forming properties. In addition, highefficiency of energy conversion, excellent field-effect mobility, goodon/off current ratios and/or excellent stability can be observed, whenthe polymers according to the invention are used in organic field effecttransistors.

U.S. Pat. No. 6,451,459 (cf. B. Tieke et al., Synth. Met. 130 (2002)115-119; Macromol. Rapid Commun. 21 (4) (2000) 182-189) describesdiketopyrrolopyrrole based polymers and copolymers comprising thefollowing units

wherein x is chosen in the range of from 0.005 to 1, preferably from0.01 to 1, and y from 0.995 to 0, preferably 0.99 to 0, and whereinx+y=1, andwherein Ar¹ and Ar² independently from each other stand for

and m, n being numbers from 1 to 10, andR¹ and R² independently from each other stand for H, C₁-C₁₈alkyl,—C(O)O—C₁-C₁₈alkyl, perfluoro-C₁-C₁₂alkyl, unsubstituted C₆-C₁₂aryl orone to three times with C₁-C₁₂alkyl, C₁-C₁₂alkoxy, or halogensubstituted C₆-C₁₂aryl, C₁-C₁₂alkyl-C₆-C₁₂aryl, orC₆-C₁₂aryl-C₁-C₁₂alkyl,R³ and R⁴ preferably stand for hydrogen, C₁-C₁₂alkyl, C₁-C₁₂alkoxy,unsubstituted C₆-C₁₂aryl or one to three times with C₁-C₁₂alkyl,C₁-C₁₂alkoxy, or halogen substituted C₆-C₁₂aryl orperfluoro-C₁-C₁₂alkyl, andR⁵ preferably stands for C₁-C₁₂alkyl, C₁-C₁₂alkoxy, unsubstitutedC₆-C₁₂aryl or one to three times with C₁-C₁₂alkyl, C₁-C₁₂alkoxy, orhalogen substituted C₆-C₁₂aryl, or perfluoro-C₁-C₁₂alkyl, and their usein EL devices. The following polymer

is explicitly disclosed in Tieke et al., Synth. Met. 130 (2002) 115-119.The following polymers

are explicitly disclosed in Macromol. Rapid Commun. 21 (4) (2000)182-189.

WO05/049695 discloses diketopyrrolopyrrole (DPP) based polymers andtheir use in PLEDs, organic integrated circuits (O-ICs), organic fieldeffect transistors (OFETs), organic thin film transistors (OTFTs),organic solar cells (O-SCs), or organic laser diodes, but fails todisclose the specific DPP based polymers of formula I.

A preferred polymer comprises a repeating unit of formula

and a repeating unit

whereinR¹ and R² are independently of each other a C₁-C₂₅alkyl group,especially a C₄-C₁₂alkyl group, which can be interrupted by one or moreoxygen atoms, and Ar¹ and Ar² are independently of each other a group offormula

wherein —Ar³— is a group of formula

whereinR⁶ is hydrogen, C₁-C₁₈alkyl, or C₁-C₁₈alkoxy, and R³² is methyl, Cl, orOMe, and R⁸ is H, C₁-C₁₈alkyl, or C₁-C₁₈alkyl which is substituted by Eand/or interrupted by D, especially C₁-C₁₈alkyl which is interrupted by—O—.

In Example 12 the preparation of the following polymer is described:

WO08/000664 describes polymers comprising (repeating) unit(s) of theformula

Ar¹ and Ar^(1′) are preferably the same and are a group of formula

andAr², Ar^(2′), Ar³, Ar^(3′), Ar⁴ and Ar^(4′) are independently of eachother a group of formula

whereinp stands for 0, 1, or 2, R³ may be the same or different within onegroup and is selected from C₁-C₂₅alkyl, which may optionally besubstituted by E and/or interrupted by D, or C₁-C₁₈alkoxy, which mayoptionally be substituted by E and/or interrupted by D;R⁴ is C₆-C₂₅alkyl, which may optionally be substituted by E and/orinterrupted by D, C₆-C₁₄aryl, such as phenyl, naphthyl, or biphenylyl,which may optionally be substituted by G, C₁-C₂₅alkoxy, which mayoptionally be substituted by E and/or interrupted by D, orC₇-C₁₅aralkyl, wherein ar may optionally be substituted by G,D is —CO—, —COO—, —S—, —SO—, —SO₂—, —O—, —NR²⁵—, wherein R²⁵ isC₁-C₁₂alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl,isobutyl, or sec-butyl;E is —OR²⁹; —SR²⁹; —NR²⁵R²⁵; —COR²⁸; —COOR²⁷; —CONR²⁵R²⁵; or —CN;wherein R²⁵, R²⁷, R²⁸ and R²⁹ are independently of each otherC₁-C₁₂alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl,isobutyl, sec-butyl, hexyl, octyl, or 2-ethyl-hexyl, or C₆-C₁₄ aryl,such as phenyl, naphthyl, or biphenylyl,G has the same preferences as E, or is C₁-C₁₈alkyl, especiallyC₁-C₁₂alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl,isobutyl, sec-butyl, hexyl, octyl, or 2-ethyl-hexyl.

The following polymers were disclosed in the Examples:

EP2034537A2, which enjoys an earlier priority date (6 Sep. 2007) thanthe present invention (31 Oct. 2008), but has been published (11 Mar.2009) after the priority date of the present invention, is directed to athin film transistor device comprising a semiconductor layer, thesemiconductor layer comprising a compound comprising a chemicalstructure represented by:

wherein each X is independently selected from S, Se, O, and NR″, each R″is independently selected from hydrogen, an optionally substitutedhydrocarbon, and a hetero-containing group, each Z is independently oneof an optionally substituted hydrocarbon, a hetero-containing group, anda halogen, d is a number which is at least 1, e is a number from zero to2; a represents a number that is at least 1; b represents a number from0 to 20; and n represents a number that is at least 1.

The following polymers are explicitly disclosed:

wherein n is the number of repeat units and can be from about 2 to about5000, R′″ and R″″ can be the same or different substituent, and whereinthe substituent is independently selected from the group consisting ofan optionally substituted hydrocarbon group and a heteroatom-containinggroup.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 contains a transfer curve for the ambipolar transistor of Example1 measured at a drain basis of (+−30 V) by sweeping the gate from −60 Vto 60 V and back.

It is the object of the present invention to provide polymers, whichshow high efficiency of energy conversion, excellent field-effectmobility, good on/off current ratios and/or excellent stability, whenused in organic field effect transistors.

Said object has been solved by polymers comprising one or more(repeating) unit(s) of the formula

whereina is an integer of 1 to 5,b is an integer of 1 to 3,c is an integer of 1 to 3,d is an integer 1, 2, or 3,e is an integer 1, 2, or 3,the sum of a, b and c is equal, or smaller than 7,Ar¹, Ar^(1′), Ar³ and Ar^(3′) are independently of each other a group offormula

or a group —Ar⁴—Ar⁵—[Ar⁶]_(f)—,Ar⁴ is a group of formula

Ar⁵ and Ar⁶ have independently of each other the meaning of Ar¹, f is 0,or an integer 1,Ar² is a group of formula

one of X¹ and X² is N and the other is CH, andR¹, R², R^(1′) and R^(2′) may be the same or different and are selectedfrom hydrogen, a C₁-C₁₀₀alkyl group, especially a C₈-C₃₆alkyl group, aC₆-C₂₄aryl, in particular phenyl or 1- or 2-naphthyl which can besubstituted one to three times with C₁-C₈alkyl, C₁-C₈thioalkoxy, and/orC₁-C₈alkoxy, or pentafluorophenyl; with the proviso that polymers offormula

having a molecular weight below 10000 are excluded, and with the furtherproviso that polymers of formula

having a molecular weight below 10000 are excluded.

In a preferred embodiment of the present invention e is 2, or 3. d ispreferably equal to e.

Polymers comprising repeating units of the formula I are preferredagainst polymers comprising repeating units of the formula III.

In a preferred embodiment the present invention is directed to a polymercomprising one or more (repeating) unit(s) of the formula

whereina is an integer of 1 to 5,Ar¹ and Ar^(1′) are independently of each other a group of formula

Ar² is a group of formula

andR¹ and R² may be the same or different and are selected from hydrogen, aC₁-C₁₀₀alkyl group, especially a C₈-C₃₆alkyl group, a C₆-C₂₄aryl, inparticular phenyl or 1- or 2-naphthyl which can be substituted one tothree times with C₁-C₈alkyl, C₁-C₈thioalkoxy, and/or C₁-C₈alkoxy, orpentafluorophenyl.

Advantageously, the polymer of the present invention, or an organicsemiconductor material, layer or component, comprising the polymer ofthe present invention can be used in OFETs.

Ar¹, Ar^(1′), Ar³ and Ar^(3′) can be the same and can be different, butare preferably the same. Ar¹, Ar^(1′), Ar³ and Ar^(3′) can be a group offormula

wherein a group of formula

is preferred.

Ar² can be a group of formula

wherein groups of formula

are preferred and a group of formula

is even more preferred. If a is equal to, or greater than 2, Ar² can becomposed of groups of formula

i.e. can, for example, be a group of formula

As indicated by the formula

can be attached to the DPP basic unit, or arranged in the polymer chainin two ways

The notation

should comprise both possibilities.

a is preferably an integer of 1 to 5, especially an integer of 1 to 3.

b is an integer of 1 to 3. c is an integer of 1 to 3. The sum of a, band c is equal, or smaller than 7.

R¹, R², R^(1′) and R^(2′) can be different, but are preferably the same.R¹, R², R^(1′) and R^(2′) can be linear, but are preferably branched.R¹, R², R^(1′) and R^(2′) are preferably a C₈-C₃₆alkyl group, especiallya C₁₂-C₂₄alkyl group, such as n-dodecyl, tridecyl, tetradecyl,pentadecyl, hexadecyl, 2-ethyl-hexyl, 2-butyl-hexyl, 2-butyl-octyl,2-hexyldecyl, 2-decyl-tetradecyl, heptadecyl, octadecyl, eicosyl,heneicosyl, docosyl, or tetracosyl. The C₈-C₃₆alkyl and C₁₂-C₂₄alkylgroup can be linear, or branched, but are preferably branched. In aparticularly preferred embodiment of the present invention R¹, R²,R^(1′) and R^(2′) are a 2-hexyldecyl or 2-decyl-tetradecyl group.

Advantageously, the groups R¹, R², R^(1′) and R^(2′) can be representedby formula

wherein m1=n1+4 and m1+n1≤22.

Chiral side chains, such as R¹, R², R^(1′) and R^(2′), can either behomochiral, or racemic, which can influence the morphology of thepolymers.

In a preferred embodiment the present invention is directed toco-polymers of the formula

wherein R¹ and R² are a branched C₈-C₃₆alkyl group, especially abranched C₁₂-C₂₄alkyl group, such as, for example, a 2-hexyldecyl or2-decyl-tetradecyl group. Said polymers have a weight average molecularweight of preferably 10,000 to 100,000 Daltons and most preferably20,000 to 60,000 Daltons. Said polymers preferably have apolydispersibility of 1.1 to 3.0, most preferred 1.5 to 2.5.

In a preferred embodiment the present invention is directed tohomopolymers of the formula

wherein R^(1′) and R^(2′) are a branched C₈-C₃₆alkyl group, especially abranched C₁₂-C₂₄alkyl group, such as, for example, a 2-hexyldecyl or2-decyl-tetradecyl group. Said polymers have a weight average molecularweight of preferably 10,000 to 100,000 Daltons and most preferably20,000 to 60,000 Daltons. Said polymers preferably have apolydispersibility of 1.1 to 3.0, most preferred 1.5 to 2.5. Saidpolymers can show ambipolarity.

In a preferred embodiment the present invention is directed to polymers,comprising one or more (repeating) unit(s) of the formula

whereina is an integer of 1 to 5, especially 1 to 3,b is an integer of 2, or 3, b′ is an integer of 2, b″ is an integer of3,one of X¹ and X² is N and the other is CH, andR¹ and R² may be the same or different and are selected from hydrogen,or a C₈-C₃₆alkyl group.

Even more preferred are polymers, comprising one or more (repeating)unit(s) of the formula

whereinR¹ and R² may be the same or different and are selected from aC₈-C₃₆alkyl group.

In a preferred embodiment of the present invention the polymer comprisestwo, or more different repeating units of formula I. Advantageously, therepeating units are selected from repeating units of formula IIa, IIb,IIc, IId, IIe, IIf, IIg and IIh. A polymer comprising repeating units offormula IIa′ and IIa″ shows, for example, excellent field effectmobility and on/off current ratio.

According to the present invention a homopolymer is a polymer derivedfrom one species of (real, implicit, or hypothetical) monomer. Manypolymers are made by the mutual reaction of complementary monomers.These monomers can readily be visualized as reacting to give an“implicit monomer”, the homopolymerisation of which would give theactual product, which can be regarded as a homopolymer. Some polymersare obtained by chemical modification of other polymers, such that thestructure of the macromolecules that constitute the resulting polymercan be thought of having been formed by the homopolymerisation of ahypothetical monomer.

Accordingly a copolymer is a polymer derived from more than one speciesof monomer, e.g. bipolymer, terpolymer, quaterpolymer, etc.

The term polymer comprises oligomers as well as polymers. The oligomersof this invention have a weight average molecular weight of <4,000Daltons. The polymers of this invention preferably have a weight averagemolecular weight of 4,000 Daltons or greater, especially 4,000 to2,000,000 Daltons, very especially 10,000 to 1,000,000 Daltons, morepreferably 10,000 to 100,000 Daltons and most preferred 20,000 to 60,000Daltons. Molecular weights are determined according to high-temperaturegel permeation chromatography (HT-GPC) using polystyrene standards. Thepolymers of this invention preferably have a polydispersibility of 1.01to 10, more preferably 1.1 to 3.0, most preferred 1.5 to 2.5.

In a preferred embodiment of the present invention the polymer is acopolymer, comprising repeating units of formula

especially, whereinA is a group of formula

COM¹ is a group of formula

andR¹, R², Ar¹, Ar^(1′) Ar² and a are as defined above.

Copolymers of formula VII can be obtained, for example, by the Suzukireaction. The condensation reaction of an aromatic boronate and ahalogenide, especially a bromide, commonly referred to as the “Suzukireaction”, is tolerant of the presence of a variety of organicfunctional groups as reported by N. Miyaura and A. Suzuki in ChemicalReviews, Vol. 95, pp. 457-2483 (1995). Preferred catalysts are2-dicyclohexylphosphino-2′,6′-di-alkoxybiphenyl/palladium(II)acetates,tri-alkyl-phosphonium salts/palladium (0) derivatives andtri-alkylphosphine/palladium (0) derivatives. Especially preferredcatalysts are 2-dicyclohexylphosphino-2′,6′-di-methoxybiphenyl(sPhos)/palladium(II)acetate and, tri-tert-butylphosphoniumtetrafluoroborate ((t-Bu)₃P*HBF₄)/tris(dibenzylideneacetone) dipalladium(0) (Pd₂(dba)₃) and tri-tert-butylphosphine(t-Bu)₃P/tris(dibenzylideneacetone) dipalladium (0) (Pd₂(dba)₃).Preferred solvents are tetrahydrofuran (THF), or mixtures of THF andtoluene. Preferred bases are aq. K₂CO₃ or aq. Na₂CO₃. This reaction canbe applied to preparing high molecular weight polymers and copolymers.

To prepare polymers corresponding to formula

whereinA is a group of formula

COM¹ is a group of formula

a is an integer of 1 to 5,n is number which results in a molecular weight of 4,000 to 2,000,000Daltons, andR¹, R², Ar¹, Ar^(1′), Ar² and a are as defined above, a dihalogenideX¹⁰-A-X¹⁰, such as a dibromide or dichloride, or diiodide, especially adibromide corresponding to formula Br-A-Br is reacted with an equimolaramount of a diboronic acid or diboronate corresponding to formula

or a dihalogenide of formula

is reacted with an equimolar amount of a diboronic acid or diboronatecorresponding to formula X¹¹-A-X¹¹, wherein X¹⁰ is halogen, especiallyBr, and X¹¹ is independently in each occurrence —B(OH)₂, —B(OY¹)₂,

—BF₃Na, —BF₃N(Y¹⁵)₄, or —BF₃K, wherein Y¹ is independently in eachoccurrence a C₁-C₁₀alkyl group and Y² is independently in eachoccurrence a C₂-C₁₀alkylene group, such as —CY³Y⁴—CY⁵Y⁶—, or—CY⁷Y⁸—CY⁹Y¹⁰—CY¹¹Y¹²—, wherein Y³, Y⁴, Y⁵, Y⁶, Y⁷, Y⁸, Y⁹, Y¹⁰, Y¹¹ andY¹² are independently of each other hydrogen, or a C₁-C₁₀alkyl group,especially —C(CH₃)₂C(CH₃)₂—, or —C(CH₃)₂CH₂C(CH₃)₂—, —CH₂C(CH₃)₂CH₂—,and Y¹³ and Y¹⁴ are independently of each other hydrogen, or aC₁-C₁₀alkyl group, Y¹⁵ is H, or a C₁-C₂₅alkyl group, which mayoptionally be interrupted by —O—, in a solvent and in the presence of acatalyst; such as, for example, under the catalytic action of Pd andtriphenylphosphine.

The reaction is typically conducted at about 0° C. to 180° C. in anaromatic hydrocarbon solvent such as toluene, xylene, anisole,chlorobenzene, fluorobenzene. Other solvents such as dimethylformamide,dioxane, dimethoxyethan, 2-methyltetrahydrofuran, cyclopentylmethyletherand tetrahydrofuran can also be used alone, or in mixtures with anaromatic hydrocarbon. Most preferred are THF or THF/toluene. An aqueousbase (such as, for example, for example, alkali and alkaline earth metalhydroxides, carboxylates, carbonates, fluorides and phosphates such assodium and potassium hydroxide, acetate, carbonate, fluoride andphosphate or also metal alcoholates), preferably sodium carbonate orbicarbonate, potassium phosphate, potassium carbonate or bicarbonate isused as the HBr scavenger. A polymerization reaction may take 0.2 to 100hours. Organic bases, such as, for example, tetraalkylammoniumhydroxide, and phase transfer catalysts, such as, for example TBAB, canpromote the activity of the boron (see, for example, Leadbeater & Marco;Angew. Chem. Int. Ed. Eng. 42 (2003) 1407 and references cited therein).Other variations of reaction conditions are given by T. I. Wallow and B.M. Novak in J. Org. Chem. 59 (1994) 5034-5037; and M. Remmers, M.Schulze, and G. Wegner in Macromol. Rapid Commun. 17 (1996) 239-252.Control of molecular weight is possible by using either an excess ofdibromide, diboronic acid, or diboronate, or a chain terminator.

The palladium catalyst is present in the reaction mixture in catalyticamounts. The term “catalytic amount” as used herein refers to an amountthat is clearly below one equivalent of dihalogenide and diboronic acidor diboronate used, preferably 0.01 to 5 mol. %, most preferably 0.01 to1 mol. %, based on the equivalents of dihalogenide and diboronic acid ordiboronate used.

The amount of phosphines or phosphonium salts in the reaction mixture ispreferably from 0.02 to 10 mol. %, most preferably 0.02 to 2 mol. %,based on the equivalents of dihalogenide and diboronic acid ordiboronate used. The preferred ratio of Pd:phosphine is 1:2. It ispreferable that at least 1.5 equivalents of said base per functionalboron group is present in the reaction mixture.

For polymerisations that are performed in a single solvent or a solventmixture, it is possible to add a secondary or tertiary co-solvent oncethe polymerisation has initiated and after a given period of time. Thepurpose of this co-solvent addition is to keep the growing polymerchains in solution during the polymerisation process. This also assistthe recovery of the polymer from the reaction mixture at the end of thereaction and therefore improve the isolated yield of the polymer.

If desired, a monofunctional aryl halide or aryl boronate may be used asa chain-terminator in such reactions, which will result in the formationof a terminal aryl group.

It is possible to control the sequencing of the monomeric units in theresulting copolymer by controlling the order and composition of monomerfeeds in the Suzuki reaction.

After polymerisation the polymer is preferably recovered from thereaction mixture, for example by conventional work-up, and purified.This can be achieved according to standard methods known to the expertand described in the literature.

The polymers of the present invention can also be sythesized by theStille coupling (see, for example, Babudri et al, J. Mater. Chem., 2004,14, 11-34; J. K. Stille, Angew. Chemie Int. Ed. Engl. 1986, 25, 508). Toprepare polymers corresponding to formula VII a dihalogenide, such as adibromide or dichloride, especially a dibromide corresponding to formulaBr-A-Br is reacted with a compound of formula

wherein X²¹ is a group —SnR²⁰⁷R²⁰⁸R²⁰⁹, in an inert solvent at atemperature in range from 0° C. to 200° C. in the presence of apalladium-containing catalyst, wherein R²⁰⁷, R²⁰⁸ and R²⁰⁹ are identicalor different and are H, or C₁-C₆alkyl, wherein two radicals optionallyform a common ring and these radicals are optionally branched orunbranched. It must be ensured here that the totality of all monomersused has a highly balanced ratio of organotin functions to halogenfunctions. In addition, it may prove advantageous to remove any excessreactive groups at the end of the reaction by end-capping withmonofunctional reagents. In order to carry out the process, the tincompounds and the halogen compounds are preferably introduced into oneor more inert organic solvents and stirred at a temperature of from 0 to200° C., preferably from 30 to 170° C. for a period of from 1 hour to200 hours, preferably from 5 hours to 150 hours. The crude product canbe purified by methods known to the person skilled in the art andappropriate for the respective polymer, for example repeatedre-precipitation or even by dialysis.

Suitable organic solvents for the process described are, for example,ethers, for example diethyl ether, dimethoxyethane, diethylene glycoldimethyl ether, tetrahydrofuran, dioxane, dioxolane, diisopropyl etherand tert-butyl methyl ether, hydrocarbons, for example hexane,isohexane, heptane, cyclohexane, benzene, toluene and xylene, alcohols,for example methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol,1-butanol, 2-butanol and tert-butanol, ketones, for example acetone,ethyl methyl ketone and isobutyl methyl ketone, amides, for exampledimethylformamide (DMF), dimethylacetamide and N-methylpyrrolidone,nitriles, for example acetonitrile, propionitrile and butyronitrile, andmixtures thereof.

The palladium and phosphine components should be selected analogously tothe description for the Suzuki variant.

Alternatively, the polymers of the present invention can also besynthesized by the Negishi reaction using zinc reagents (A-(ZnX²²)₂,wherein X²² is halogen) and halides or triflates (COM¹-(X²³)₂, whereinX²³ is halogen or triflate). Reference is, for example, made to E.Negishi et al., Heterocycles 18 (1982) 117-22.

The polymers, wherein R¹ and/or R² are hydrogen can be obtained by usinga protecting group which can be removed after polymerization (see, forexample, EP-A-0648770, EP-A-0648817, EP-A-0742255, EP-A-0761772,WO98/32802, WO98/45757, WO98/58027, WO99/01511, WO00/17275, WO00/39221,WO00/63297 and EP-A-1086984). Conversion of the pigment precursor intoits pigmentary form is carried out by means of fragmentation under knownconditions, for example thermally, optionally in the presence of anadditional catalyst, for example the catalysts described in WO00/36210.

An example of such a protecting group is group of formula

wherein L is any desired group suitable for imparting solubility.

L is preferably a group of formula

wherein Z¹, Z² and Z³ are independently of each other C₁-C₆alkyl,Z⁴ and Z⁸ are independently of each other C₁-C₆alkyl, C₁-C₆alkylinterrupted by oxygen, sulfur or N(Z¹²)₂, or unsubstituted orC₁-C₆alkyl-, C₁-C₆alkoxy-, halo-, cyano- or nitro-substituted phenyl orbiphenyl,Z⁵, Z⁶ and Z⁷ are independently of each other hydrogen or C₁-C₆alkyl,Z⁹ is hydrogen, C₁-C₆alkyl or a group of formula

Z¹⁰ and Z¹¹ are each independently of the other hydrogen, C₁-C₆alkyl,C₁-C₆alkoxy, halogen, cyano, nitro, N(Z¹²)₂, or unsubstituted or halo-,cyano-, nitro-, C₁-C₆alkyl- or C₁-C₆alkoxy-substituted phenyl,Z¹² and Z¹³ are C₁-C₆alkyl, Z¹⁴ is hydrogen or C₁-C₆alkyl, and Z¹⁵ ishydrogen, C₁-C₆alkyl, or unsubstituted or C₁-C₆alkyl-substituted phenyl,Q is p,q-C₂-C₆alkylene unsubstituted or mono- or poly-substituted byC₁-C₆alkoxy,C₁-C₆alkylthio or C₂-C₁₂dialkylamino, wherein p and q are differentposition numbers,X is a hetero atom selected from the group consisting of nitrogen,oxygen and sulfur, m′ being the number 0 when X is oxygen or sulfur andm being the number 1 when X is nitrogen, andL¹ and L² are independently of each other unsubstituted or mono- orpoly-C₁-C₁₂alkoxy-, —C₁-C₁₂alkylthio-, —C₂-C₂₄dialkylamino-,—C₆-C₁₂aryloxy-, —C₆-C₁₂arylthio-, —C₇-C₂₄alkylarylamino- or—C₁₂-C₂₄diarylamino-substituted C₁-C₆alkyl or[—(p′,q′-C₂-C₆alkylene)—Z—]_(n′)—C₁-C₆alkyl, n′ being a number from 1 to1000, p′ and q′ being different position numbers, each Z independentlyof any others being a hetero atom oxygen, sulfur orC₁-C₁₂alkyl-substituted nitrogen, and it being possible forC₂-C₆alkylene in the repeating [—C₂-C₆alkylene-Z—] units to be the sameor different,and L₁ and L₂ may be saturated or unsaturated from one to ten times, maybe uninterrupted or interrupted at any location by from 1 to 10 groupsselected from the group consisting of —(C═O)— and —C₆H₄—, and may carryno further substituents or from 1 to 10 further substituents selectedfrom the group consisting of halogen, cyano and nitro. Most preferred Lis a group of formula

The synthesis of the compounds of formula Br-A-Br is described inWO05/049695, WO08/000664, and WO09/047104, or can be done in analogy tothe methods described therein. The synthesis of N-aryl substitutedcompounds of formula Br-A-Br can be done in analogy to the methodsdescribed in U.S. Pat. No. 5,354,869 and WO03/022848.

In another embodiment the present invention is directed to polymers offormula III.

In said embodiment polymers are preferred, comprising one or more(repeating) unit(s) of the formula

whereinR^(1′) and R^(2′) may be the same or different and are selected from aC₈-C₃₆alkyl group.

In another preferred embodiment the present invention is directed tohomopolymers of the formula

or copolymers of formula

wherein R¹, R², R^(1′) and R^(2′) are a branched C₈-C₃₆alkyl group,especially a branched C₁₂-C₂₄alkyl group, or a copolymer of formula

having a Mw of 51,500 and a Polydispersity of 2.0 (measured by HT-GPC).

The polymers comprising repeating units of formula III are preferablyhomopolymers, which can be prepared by dehalogenative polycondensation(reductive coupling) of the corresponding dihaloaromatic compounds suchas Br-A-Br with 0-valent Ni complexes (Yamamoto coupling reaction). AsNickel source bis(cyclooctadiene)nickel can be used in combination withbipyridine, triarylphosphine or trialyklphosphine. Reference is, forexample, made to T. Yamamoto, et al., Synthetic Metals (1993), 55(2-3),1214-20.

Alternatively, such polymers can be prepared by reacting a dihalogenideX¹⁰-A-X¹⁰ with an equimolar amount of a diboronic acid or diboronatecorresponding to formula X¹¹-A-X¹¹.

A further embodiment of the present invention is directed to compoundsof formula

whereind is an integer 1, 2, or 3,e is an integer 1, 2, or 3,Ar³ and Ar^(3′) are independently of each other a group of formula

or a group —Ar⁴—Ar⁵—[Ar⁶]_(f)—,Ar⁴ is a group of formula

Ar⁵ and Ar⁶ have independently of each other the meaning of Ar³, f is 0,or an integer 1,R1′ and R2′ are as defined in claim 1,X¹² is —B(OH)₂, —B(OY¹)₂,

—BF₃Na, —BF₃N(Y¹⁵)₄, or —BF₃K, wherein Y¹ is independently in eachoccurrence a C₁-C₁₀alkyl group and Y² is independently in eachoccurrence a C₂-C₁₀alkylene group, such as —CY³Y⁴—CY⁵Y⁶—, or—CY⁷Y⁸—CY⁹Y¹⁰—CY¹¹Y¹²—, wherein Y³, Y⁴, Y⁵, Y⁶, Y⁷, Y⁸, Y⁹, Y¹⁰, Y¹¹ andY¹² are independently of each other hydrogen, or a C₁-C₁₀alkyl group,especially —C(CH₃)₂C(CH₃)₂—, or —C(CH₃)₂CH₂C(CH₃)₂— and Y¹⁵ is H, or aC₁-C₂₅alkyl group, which may optionally be interrupted by O.

The compounds of formula X represent intermediates for the synthesis ofthe polymers of the present invention. Specific examples of suchcompounds are shown below:

The polymers of the invention can be used as the semiconductor layer insemiconductor devices. Accordingly, the present invention also relatesto semiconductor devices, comprising a polymer of the present invention,or an organic semiconductor material, layer or component. Thesemiconductor device is especially an organic field effect transistor(OFET).

There are numerous types of semiconductor devices. Common to all is thepresence of one or more semiconductor materials. Semiconductor deviceshave been described, for example, by S. M. Sze in Physics ofSemiconductor Devices, 2^(nd) edition, John Wiley and Sons, New York(1981). Such devices include rectifiers, transistors (of which there aremany types, including p-n-p, n-p-n, and thin-film transistors), lightemitting semiconductor devices (for example, organic light emittingdiodes in display applications or backlight in e.g. liquid crystaldisplays), photoconductors, current limiters, solar cells, thermistors,p-n junctions, field-effect diodes, Schottky diodes, and so forth. Ineach semiconductor device, the semiconductor material is combined withone or more metals, metal oxides, such as, for example, indium tin oxide(ITO), and/or insulators to form the device. Semiconductor devices canbe prepared or manufactured by known methods such as, for example, thosedescribed by Peter Van Zant in Microchip Fabrication, Fourth Edition,McGraw-Hill, New York (2000). In particular, organic electroniccomponents can be manufactured as described by D. R. Gamota et al. inPrinted Organic and Molecular Electronics, Kluver Academic Publ.,Boston, 2004.

A particularly useful type of transistor device, the thin-filmtransistor (TFT), generally includes a gate electrode, a gate dielectricon the gate electrode, a source electrode and a drain electrode adjacentto the gate dielectric, and a semiconductor layer adjacent to the gatedielectric and adjacent to the source and drain electrodes (see, forexample, S. M. Sze, Physics of Semiconductor Devices, 2^(nd) edition,John Wiley and Sons, page 492, New York (1981)). These components can beassembled in a variety of configurations. More specifically, an OFET hasan organic semiconductor layer.

Typically, a substrate supports the OFET during manufacturing, testing,and/or use. Optionally, the substrate can provide an electrical functionfor the OFET. Useful substrate materials include organic and inorganicmaterials. For example, the substrate can comprise silicon materialsinclusive of various appropriate forms of silicon, inorganic glasses,ceramic foils, polymeric materials (for example, acrylics, polyester,epoxies, polyamides, polycarbonates, polyimides, polyketones,poly(oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1,4-phenylene)(sometimes referred to as poly(ether ether ketone) or PEEK),polynorbornenes, polyphenyleneoxides, poly(ethylenenaphthalenedicarboxylate) (PEN), poly(ethylene terephthalate) (PET),poly(phenylene sulfide) (PPS)), filled polymeric materials (for example,fiber-reinforced plastics (FRP)), and coated metallic foils.

The gate electrode can be any useful conductive material. For example,the gate electrode can comprise doped silicon, or a metal, such asaluminum, chromium, gold, silver, nickel, palladium, platinum, tantalum,and titanium. Conductive oxides, such as indium tin oxide, or conductinginks/pastes comprised of carbon black/graphite or colloidal silverdispersions, optionally containing polymer binders can also be used.Conductive polymers also can be used, for example polyaniline orpoly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS). Inaddition, alloys, combinations, and multilayers of these materials canbe useful. In some OFETs, the same material can provide the gateelectrode function and also provide the support function of thesubstrate. For example, doped silicon can function as the gate electrodeand support the OFET.

The gate dielectric is generally provided on the gate electrode. Thisgate dielectric electrically insulates the gate electrode from thebalance of the OFET device. Useful materials for the gate dielectric cancomprise, for example, an inorganic electrically insulating material.

The gate dielectric (insulator) can be a material, such as, an oxide,nitride, or it can be a material selected from the family offerroelectric insulators (e.g. organic materials such as poly(vinylidenefluoride/trifluoroethylene or poly(m-xylylene adipamide)), or it can bean organic polymeric insulator (e.g. poly(methacrylate)s,poly(acrylate)s, polyimides, benzocyclobutenes (BCBs), parylenes,polyvinylalcohol, polyvinylphenol (PVP), polystyrenes, polyester,polycarbonates) as for example described in J. Veres et al. Chem. Mat.2004, 16, 4543 or A. Facchetti et al. Adv. Mat. 2005, 17, 1705. Specificexamples of materials useful for the gate dielectric includestrontiates, tantalates, titanates, zirconates, aluminum oxides, siliconoxides, tantalum oxides, titanium oxides, silicon nitrides, bariumtitanate, barium strontium titanate, barium zirconate titanate, zincselenide, and zinc sulphide, including but not limited toPbZr_(x)Ti_(1-x)O₃ (PZT), Bi₄Ti₃O₁₂, BaMgF₄, Ba(Zr_(1-x)Ti_(x))O₃ (BZT).In addition, alloys, hybride materials (e.g. polysiloxanes ornanoparticle-filled polymers) combinations, and multilayers of thesematerials can be used for the gate dielectric. The thickness of thedielectric layer is, for example, from about 10 to 1000 nm, with a morespecific thickness being about 100 to 500 nm, providing a capacitance inthe range of 0.1-100 nanofarads (nF).

The source electrode and drain electrode are separated from the gateelectrode by the gate dielectric, while the organic semiconductor layercan be over or under the source electrode and drain electrode. Thesource and drain electrodes can be any useful conductive materialfavourably providing a low resistance ohmic contact to the semiconductorlayer. Useful materials include most of those materials described abovefor the gate electrode, for example, aluminum, barium, calcium,chromium, gold, silver, nickel, palladium, platinum, titanium,polyaniline, PEDOT:PSS, other conducting polymers, alloys thereof,combinations thereof, and multilayers thereof. Some of these materialsare appropriate for use with n-type semiconductor materials and othersare appropriate for use with p-type semiconductor materials, as is knownin the art.

The thin film electrodes (that is, the gate electrode, the sourceelectrode, and the drain electrode) can be provided by any useful meanssuch as physical vapor deposition (for example, thermal evaporation orsputtering) or (ink jet) printing methods. The patterning of theseelectrodes can be accomplished by known methods such as shadow masking,additive photolithography, subtractive photolithography, printing,microcontact printing, and pattern coating.

The present invention further provides an organic field effecttransistor device comprising a plurality of electrically conducting gateelectrodes disposed on a substrate; a gate insulator layer disposed onsaid electrically conducting gate electrodes; a plurality of sets ofelectrically conductive source and drain electrodes disposed on saidinsulator layer such that each of said sets is in alignment with each ofsaid gate electrodes; an organic semiconductor layer disposed in thechannel between source and drain electrodes on said insulator layersubstantially overlapping said gate electrodes; wherein said organicsemiconductor layer comprises a polymer of the present invention, or amixture containing a polymer of the present invention.

The present invention further provides a process for preparing a thinfilm transistor device comprising the steps of:

depositing a plurality of electrically conducting gate electrodes on asubstrate;

depositing a gate insulator layer on said electrically conducting gateelectrodes;

depositing a plurality of sets of electrically conductive source anddrain electrodes on said layer such that each of said sets is inalignment with each of said gate electrodes;

depositing a layer of a polymer of the present invention on saidinsulator layer such that said layer of the compound of the presentinvention, or a mixture containing a polymer of the present invention,substantially overlaps said gate electrodes; thereby producing the thinfilm transistor device.

A mixture containing a polymer of the present invention results in asemi-conducting layer comprising a polymer of the present invention(typically 5% to 99.9999% by weight, especially 20 to 85% by weight) andat least another material. The other material can be, but is notrestricted to a fraction of the same polymer of the present inventionwith different molecular weight, another polymer of the presentinvention, a semi-conducting polymer, organic small molecules, carbonnanotubes, a fullerene derivative, inorganic particles (quantum dots,quantum rods, quantum tripods, TiO₂, ZnO etc.), conductive particles(Au, Ag etc.), insulator materials like the ones described for the gatedielectric (PET, PS etc.).

Accordingly, the present invention also relates to an organicsemiconductor material, layer or component, comprising a polymeraccording to the present invention.

The polymers of the present invention can be blended with smallmolecules described, for example, in European patent application no.09155919.5, WO09/047104, U.S. Pat. No. 6,690,029, WO2007082584, andWO2008107089.

WO2007082584:

WO2008107089:

wherein one of Y₁ and Y₂ denotes —CH═ or ═CH— and the other denotes —X—,one of Y₃ and Y₄ denotes —CH═ or ═CH— and the other denotes —X—,X is —O—, —S—, —Se— or —NR′″—,R₃ is cyclic, straight-chain or branched alkyl or alkoxy having 1 to 20C-atoms, or aryl having 2-30 C-atoms, all of which are optionallyfluorinated or perfluorinated,R′ is H, F, Cl, Br, I, CN, straight-chain or branched alkyl or alkoxyhaving 1 to 20 C-atoms and optionally being fluorinated orperfluorinated, optionally fluorinated or perfluorinated aryl having 6to 30 C-atoms, or CO₂R″, with R″ being H, optionally fluorinated alkylhaving 1 to 20 C-atoms, or optionally fluorinated aryl having 2 to 30C-atoms,R′″ is H or cyclic, straight-chain or branched alkyl with 1 to 10C-atoms, y is 0, or 1, x is 0, or 1.

The polymer can contain a small molecule, or a mixture of two, or moresmall molecule compounds.

Alternatively, an OFET is fabricated by, for example, by solutiondeposition of a polymer on a highly doped silicon substrate covered witha thermally grown oxide layer followed by vacuum deposition andpatterning of source and drain electrodes.

In yet another approach, an OFET is fabricated by deposition of sourceand drain electrodes on a highly doped silicon substrate covered with athermally grown oxide and then solution deposition of the polymer toform a thin film.

The gate electrode could also be a patterned metal gate electrode on asubstrate or a conducting material such as, a conducting polymer, whichis then coated with an insulator applied either by solution coating orby vacuum deposition on the patterned gate electrodes.

Any suitable solvent can be used to dissolve, and/or disperse thepolymers of the present application, provided it is inert and can beremoved partly, or completely from the substrate by conventional dryingmeans (e.g. application of heat, reduced pressure, airflow etc.).Suitable organic solvents for processing the semiconductors of theinvention include, but are not limited to, aromatic or aliphatichydrocarbons, halogenated such as chlorinated or fluorinatedhydrocarbons, esters, ethers amides, such as chloroform,tetrachloroethane, tetrahydrofuran, toluene, tetraline, decaline,anisole, xylene, ethyl acetate, methyl ethyl ketone, dimethyl formamide,chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, propyleneglycol monomethyl ether acetate (PGMEA) and mixtures thereof. Preferredsolvents are xylene, toluene, tetraline, decaline, chlorinated ones suchas chloroform, chlorobenzene, ortho-dichlorobenzene, trichlorobenzeneand mixtures thereof. The solution, and/or dispersion is then applied bya method, such as, spin-coating, dip-coating, screen printing,microcontact printing, doctor blading or other solution applicationtechniques known in the art on the substrate to obtain thin films of thesemiconducting material.

The term “dispersion” covers any composition comprising thesemiconductor material of the present invention, which is not fullydissolved in a solvent. The dispersion can be done selecting acomposition including at least a polymer of the present invention, or amixture containing a polymer of the present invention, and a solvent,wherein the polymer exhibits lower solubility in the solvent at roomtemperature but exhibits greater solubility in the solvent at anelevated temperature, wherein the composition gels when the elevatedtemperature is lowered to a first lower temperature without agitation;

-   -   dissolving at the elevated temperature at least a portion of the        polymer in the solvent; lowering the temperature of the        composition from the elevated temperature to the first lower        temperature; agitating the composition to disrupt any gelling,        wherein the agitating commences at any time prior to,        simultaneous with, or subsequent to the lowering the elevated        temperature of the composition to the first lower temperature;        depositing a layer of the composition wherein the composition is        at a second lower temperature lower than the elevated        temperature; and drying at least partially the layer.

The dispersion can also be constituted of (a) a continuous phasecomprising a solvent, a binder resin, and optionally a dispersing agent,and (b) a disperse phase comprising a polymer of the present invention,or a mixture containing a polymer of the present invention. The degreeof solubility of the polymer of the present invention in the solvent mayvary for example from 0% to about 20% solubility, particularly from 0%to about 5% solubility.

Preferably, the thickness of the organic semiconductor layer is in therange of from about 5 to about 1000 nm, especially the thickness is inthe range of from about 10 to about 100 nm.

The polymers of the invention can be used alone or in combination as theorganic semiconductor layer of the semiconductor device. The layer canbe provided by any useful means, such as, for example, vapor deposition(for materials with relatively low molecular weight) and printingtechniques. The compounds of the invention may be sufficiently solublein organic solvents and can be solution deposited and patterned (forexample, by spin coating, dip coating, ink jet printing, gravureprinting, flexo printing, offset printing, screen printing, microcontact(wave)-printing, drop or zone casting, or other known techniques).

The polymers of the invention can be used in integrated circuitscomprising a plurality of OTFTs, as well as in various electronicarticles. Such articles include, for example, radio-frequencyidentification (RFID) tags, backplanes for flexible displays (for usein, for example, personal computers, cell phones, or handheld devices),smart cards, memory devices, sensors (e.g. light-, image-, bio-, chemo-,mechanical- or temperature sensors), especially photodiodes, or securitydevices and the like. Due to its solid state fluorescence the materialcan also be used in Organic Light Emitting Transistors (OLET).

A further aspect of the present invention is an organic semiconductormaterial, layer or component comprising one or more polymers of thepresent invention. A further aspect is the use of the polymers ormaterials of the present invention in an organic field effect transistor(OFET). A further aspect is an OFET comprising a polymer or material ofthe present invention.

The polymers of the present invention are typically used as organicsemiconductors in form of thin organic layers or films, preferably lessthan 30 microns thick. Typically the semiconducting layer of the presentinvention is at most 1 micron (=1 μm) thick, although it may be thickerif required. For various electronic device applications, the thicknessmay also be less than about 1 micron thick. For example, for use in anOFET the layer thickness may typically be 100 nm or less. The exactthickness of the layer will depend, for example, upon the requirementsof the electronic device in which the layer is used.

For example, the active semiconductor channel between the drain andsource in an OFET may comprise a layer of the present invention.

An OFET device according to the present invention preferably comprises:

-   -   a source electrode,    -   a drain electrode,    -   a gate electrode,    -   a semiconducting layer,    -   one or more gate insulator layers, and    -   optionally a substrate, wherein the semiconductor layer        comprises one or more polymers of the present invention.

The gate, source and drain electrodes and the insulating andsemiconducting layer in the OFET device may be arranged in any sequence,provided that the source and drain electrode are separated from the gateelectrode by the insulating layer, the gate electrode and thesemiconductor layer both contact the insulating layer, and the sourceelectrode and the drain electrode both contact the semiconducting layer.

Preferably the OFET comprises an insulator having a first side and asecond side, a gate electrode located on the first side of theinsulator, a layer comprising a polymer of the present invention locatedon the second side of the insulator, and a drain electrode and a sourceelectrode located on the polymer layer.

The OFET device can be a top gate device or a bottom gate device.

Suitable structures and manufacturing methods of an OFET device areknown to the skilled in the art and are described in the literature, forexample in WO03/052841.

The gate insulator layer may comprise for example a fluoropolymer, likee.g. the commercially available Cytop 809M®, or Cytop 107M® (from AsahiGlass). Preferably the gate insulator layer is deposited, e.g. byspin-coating, doctor blading, wire bar coating, spray or dip coating orother known methods, from a formulation comprising an insulator materialand one or more solvents with one or more fluoro atoms (fluorosolvents),preferably a perfluorosolvent. A suitable perfluorosolvent is e.g. FC75®(available from Acros, catalogue number 12380). Other suitablefluoropolymers and fluorosolvents are known in prior art, like forexample the perfluoropolymers Teflon AF® 1600 or 2400 (from DuPont), orFluoropel® (from Cytonix) or the perfluorosolvent FC 43® (Acros, No.12377).

The semiconducting layer comprising a polymer of the present inventionmay additionally comprise at least another material. The other materialcan be, but is not restricted to another polymer of the presentinvention, a semi-conducting polymer, a polymeric binder, organic smallmolecules different from a polymer of the present invention, carbonnanotubes, a fullerene derivative, inorganic particles (quantum dots,quantum rods, quantum tripods, TiO₂, ZnO etc.), conductive particles(Au, Ag etc.), and insulator materials like the ones described for thegate dielectric (PET, PS etc.). As stated above, the semiconductivelayer can also be composed of a mixture of one or more polymers of thepresent invention and a polymeric binder. The ratio of the polymers ofthe present invention to the polymeric binder can vary from 5 to 95percent. Preferably, the polymeric binder is a semicristalline polymersuch as polystyrene (PS), high-density polyethylene (HDPE),polypropylene (PP) and polymethylmethacrylate (PMMA). With thistechnique, a degradation of the electrical performance can be avoided(cf. WO2008/001123A1).

Digital circuits are largely based on complimentary metal oxide (CMOS)structures that use both p-type and n-type unipolar transistors. Theadvantages of CMOS circuits are lower power dissipation, greater speed,and greater tolerance of variability and shifts in transistor operatingcharacteristics. These CMOS circuits may be constructed using unipolartransistors with either p-type or n-type semiconductors.

For example poly[2-methoxyx-5-(3′,7′-dimethyloctyloxy)]-p-phenylenevinylene (OC₁C₁₀-PPV) p-type semiconductor and [6,6]-phenyl C₆₁-butyricacid methyl ester (PCBM) n-type semiconductor each show mobilities ofabout 10⁻² cm²/Vs when each is used as an unipolar transistor. Howeverthe mobility of these semiconductors decreases to 10⁻⁰⁴ cm2/Vs and 10⁻⁰⁵cm2/Vs, respectively, in ambipolar transistors with a mixture ofOC₁C₁₀-PPV and PCBM [E. J. Meijer, et al Nature Materials, 2003, Vol. 2page 678). WO2008/122778 discloses an improved blend composition toachieve a balanced mobility but still the mobility is low. At theselevels, the mobility is too low to have practical use for electronicdevices such as radio frequency identification tags.

Fabrication of discrete organic n- and p-channel transistors withlateral dimensions of a few micrometers, typically required for largescale integration, is still very challenging.

In order to design more efficient circuits based on solution processabletransistors, there is an urgent need for complementary technology, whereboth p-type and n-type operation are realized as single componenttransistor. Ideally, the transistor should exhibit high mobility,balanced on current and/or balanced mobility.

US20080099758 and WO20080246095 disclose single component ambipolarpolymers and monomers which show hole and electron mobilities in theorder of 2×10⁻⁴ cm²/Vs,

Adv. Material. 2008, 20, 2217-2224 discloses as example a homopolymeraccording formula

measured in different device configurations that reach maximum values ofhole mobility of 0.05 cm²/Vs the electron mobility was not determinedusing bottom contact gold electrodes. Using top contact gold electrodes0.11 cm²/Vs for hole mobility and electron mobilities in the range of0.04-0.09 cm²/Vs are determined. The polymers of the present inventioncan show up a factor 5 to 10 better hole and electron mobility in abottom gate bottom contact device structure. Due to low contactresistance of this type of polymers the ambipolarity can be induced by asingle contact material like gold for both type of carriers, no longerrelying on reactive low work function metals such as Ca, Mg forinjecting electrons. Injection is even achieved with Ag and Cu or alloysthereof as source and drain electrodes.

For example, using top contact gold electrodes 0.43 cm²/Vs for holemobility and electron mobilities in the range of 0.35 cm²/Vs aredetermined for the polymer of example 1:

Accordingly, the present invention also provides an ambipolar organicfield effect transistor (OFET), comprising a p-type and n-typebehaviour, especially an organic thin film transistor (OTFT), comprisinga gate electrode, a gate insulating layer, an organic active layer, andsource/drain electrodes on a substrate, wherein the organic active layerincludes a polymer of the present invention. Preferably, the activelayer is composed of a polymer of the present invention. The compositionof the active (semiconductor) layer is such as to transport bothelectrons and holes, with the mobility of the holes being substantiallyequal to the mobility of the electrons, such that the transistorsubstantially exhibits ambipolarity in its transfer characteristics.

The ambipolar OTFT may include a substrate, a gate electrode, a gateinsulating layer, source/drain electrodes, and an active layer, oralternatively may include a substrate, a gate electrode, a gateinsulating layer, an active layer, and source/drain electrodes, butexample embodiments may not be limited thereto.

In order to form the organic active layer using the polymer of thepresent invention, a composition for the organic active layer includingchloroform or chlorobenzene may be used. Examples of the solvent used inthe composition for the organic active layer may include chloroform,chlorobenzene, dichlorobenzene, trichlorobenzene, and toluene.

Examples of the process of forming the organic active layer may include,but may not be limited to, screen printing, printing, spin coating,dipping or ink jetting. As such, in the gate insulating layer includedin the ambipolar OTFT any insulator having a high dielectric constantmay be used as long as it is typically known in the art. Specificexamples thereof may include, but may not be limited to, a ferroelectricinsulator, including Ba_(0.33)Sr_(0.66)TiO₃ (BST: Barium StrontiumTitanate), Al₂O₃, Ta₂O₅, La₂O₅, Y₂O₅, or TiO₂, an inorganic insulator,including PbZr_(0.33)Ti_(0.66)O₃ (PZT), Bi₄Ti₃O₁₂, BaMgF₄,SrBi₂(TaNb)₂O₉, Ba(ZrTi)O₃(BZT), BaTiO₃, SrTiO₃, Bi₄Ti₃O₁₂, SiO₂,SiN_(x), or AlON, or an organic insulator, including polyimide,benzocyclobutane (BCB), parylene, polyvinylalcohol, or polyvinylphenol.In the gate electrode and the source/drain electrodes included in theambipolar OTFT of the present invention, a typical metal may be used,specific examples thereof include, but are not limited to, gold (Au),silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), and indium tinoxide (ITO). Preferably, the material of at least one of the gate,source and drain electrodes is selected from the group Cu, Ag, Au oralloys thereof. Examples of material for the substrate in the ambipolarOTFT of the present invention may include, but may not be limited to,glass, polyethylenenaphthalate (PEN), polyethyleneterephthalate (PET),polycarbonate, polyvinylalcohol, polyacrylate, polyimide,polynorbornene, or polyethersulfone (PES).

The present invention also provides an electronic device comprising theambipolar organic field effect transistor (OFET), especially the organicthin film transistor (OTFT) of the present invention. Because thepolymer of the present invention serves to improve the devicecharacteristics of an ambipolar organic thin film transistor, thepolymer may be effectively used to fabricate a variety of electronicdevices, including liquid crystal display (LCD) devices, photovoltaicdevices, organic light-emitting devices (OLEDs), sensors, memory devicesand/or integrated circuits.

The method of fabricating an ambipolar organic thin film transistor mayinclude forming a gate electrode, a gate insulating layer, an organicactive layer, and source/drain electrodes on a substrate, wherein theorganic active layer includes the polymer of the present invention. Theorganic active layer may be formed into a thin film through screenprinting, printing, spin coating, dipping or ink jetting. The insulatinglayer may be formed using material selected from the group consisting ofa ferroelectric insulator, including Ba_(0.33)Sr_(0.66)TiO₃ (BST: BariumStrontium Titanate), Al₂O₃, Ta₂O₅, La₂O₅, Y₂O₅, or TiO₂, an inorganicinsulator, including PbZr_(0.33)Ti_(0.66)O₃ (PZT), Bi₄Ti₃O₁₂, BaMgF₄,SrBi₂(TaNb)₂O₉, Ba(ZrTi)O₃(BZT), BaTiO₃, SrTiO₃, Bi₄Ti₃O₁₂, SiO₂,SiN_(x), or AlON, or an organic insulator, including polyimide,benzocyclobutane (BCB), parylene, polyvinylalcohol, or polyvinylphenolThe substrate may be formed using material selected from the groupconsisting of glass, polyethylenenaphthalate (PEN),polyethyleneterephthalate (PET), polycarbonate, polyvinylalcohol,polyacrylate, polyimide, polynorbornene, and polyethersulfone (PES). Thegate electrode and the source/drain electrodes may be formed usingmaterial selected from the group consisting of gold (Au), silver (Ag),copper (Cu), aluminum (Al), nickel (Ni), and indium tin oxide (ITO).

The polymers of the present invention may also be used in organicphotovoltaic (PV) devices (solar cells). Accordingly, the inventionprovides PV devices comprising a polymer according to the presentinvention.

The PV device comprise in this order:

(a) a cathode (electrode),

(b) optionally a transition layer, such as an alkali halogenide,especially lithium fluoride,

(c) a photoactive layer,

(d) optionally a smoothing layer,

(e) an anode (electrode),

(f) a substrate.

The photoactive layer comprises the polymers of the present invention.Preferably, the photoactive layer is made of a conjugated polymer of thepresent invention, as an electron donor and an acceptor material, like afullerene, particularly a functionalized fullerene PCBM, as an electronacceptor.

For heterojunction solar cells the active layer comprises preferably amixture of a polymer of the present invention and a fullerene, such as[60]PCBM (=6,6-phenyl-C₆₁-butyric acid methyl ester), or [70]PCBM, in aweight ratio of 1:1 to 1:3.

Further preferred is an integrated circuit comprising a field effecttransistor according to the present invention.

The following examples are included for illustrative purposes only anddo not limit the scope of the claims. Unless otherwise stated, all partsand percentages are by weight.

Weight-average molecular weight (Mw) and polydispersity (Mw/Mn=PD) aredetermined by Heat Temperature Gel Permeation Chromatography (HT-GPC)[Apparatus: GPC PL 220 from Polymer laboratories (Church Stretton, UK;now Varian) yielding the responses from refractive index (RI),Chromatographic conditions: Column: 3 “PLgel Olexis” column from PolymerLaboratories (Church Stretton, UK); with an average particle size of 13μm (dimensions 300×8 mm I.D.) Mobile phase: 1,2,4-trichlorobenzenepurified by vacuum distillation and stabilised by butylhydroxytoluene(BHT, 200 mg/l), Chromatographic temperature: 150° C.; Mobile phaseflow: 1 ml/min; Solute concentration: about 1 mg/ml; Injection volume:200 μl; Detection: RI, Procedure of molecular weight calibration:Relative calibration is done by use of a set of 10 polystyrenecalibration standards obtained from Polymer Laboratories (ChurchStretton, UK) spanning the molecular weight range from 1,930,000Da-5,050 Da, i.e., PS 1,930,000, PS 1,460,000, PS 1,075,000, PS 560,000,PS 330,000, PS 96,000, PS 52,000, PS 30,300, PS 10,100, PS 5,050 Da. Apolynomic calibration is used to calculate the molecular weight.

All polymer structures given in the examples below are idealizedrepresentations of the polymer products obtained via the polymerizationprocedures described. If more than two components are copolymerized witheach other sequences in the polymers can be either alternating or randomdepending on the polymerisation conditions.

EXAMPLES Example 1

Starting material 1 for polymer 3 is prepared according to Example 2a ofWO2008000664. In a three neck-flask, 1.45 g of potassium phosphate(K₃PO₄) dissolved in 5 ml of water (previously degassed) is added to adegassed solution of 2.07 g of 1, 0.74 g of 2,5-thiopheneboronic acidbis(pinacol) ester, 32.1 mg of tri-tert-butylphosphoniumtetrafluoroborate ((t-Bu)₃P*HBF₄) and 52.2 mg oftris(dibenzylideneacetone) dipalladium (0) (Pd₂(dba)₃) in 20 ml oftetrahydrofuran. The reaction mixture is heated at reflux temperaturefor two hours. Subsequently, 18 mg bromo-thiophene and 20 minutes later24 mg thiophene-boronic acid pinacol ester are added to stop thepolymerisation reaction. The reaction mixture is cooled to roomtemperature and precipitated in methanol. The residue is purified bysoxhlet extraction using pentane and heptane and the polymer is thenextracted with cyclohexane to give 1.45 g of a dark powder. Mw=39,500,Polydispersity=2.2 (measured by HT-GPC).

Application Example 1a

Bottom-gate thin film transistor (TFT) structures with p-Si gate (10 cm)are used for all experiments. A high-quality thermal SiO₂ layer of 300nm thickness served as gate-insulator of C_(i)=32.6 nF/cm² capacitanceper unit area. Source and drain electrodes are patterned byphotolithography directly on the gate-oxide. Gold source drainelectrodes defining channels of width W=10 mm and varying lengths L=4,8, 15, 30 μm are used. Prior to deposition of the organic semiconductorthe SiO₂ surface is derivatized either with hexadimethylsilazane (HMDS)by exposing to a saturated silane vapour at 160° C. for 2 hours, ortreating the substrate at 60° C. with a 0.1 m solution ofoctadecyltrichlorosilane (OTS) in toluene for 20 minutes. After rinsingwith iso-propanol the substrates are dried.

Transistor Performance in Xylene

The semiconductor thin film is prepared either by spin-coating, or dropcasting the DPP derivative of the formula 3 obtained in example 1 in a1% (w/w) solution in xylene. Before use the solution is filtered througha 0.2 m filter. The spin coating is accomplished at a spinning speed of800 rpm (rounds per minute) for about 20 seconds in ambient conditions.The devices are dried at 80° C. for 1 hour before evaluation.

The transistor behaviour is measured on an automated transistor prober(TP-10). From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 2.4×10⁻¹ cm²/Vs with anon/off current ratio of 8.5×10⁵ can be determined. The threshold voltageis at −2.7 V.

Transistor Performance in Chloroform

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 3 obtained in example 1 in a0.5% (w/w) solution in chloroform. The spin coating is accomplished at aspinning speed of 3000 rpm (rounds per minute) for about 20 seconds inambient conditions. The devices are dried at 120° C. for 15 minutesbefore evaluation.

The transistor behaviour is measured on an automated transistor prober(TP-10).

From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 2.1×10⁻¹ cm²/Vs with anon/off current ratio of 5.7×10⁶ can be determined. The threshold voltageis at 2.0 V.

Measurement of the Ambipolarity

Application Example 1b

The ambipolar transistor just described in application example 1 usingo-xylene as solvent is measured at a drain bias of (+−30 V) by sweepingthe gate from −60 V to 60 V and back. The FIGURE shows the transfercurve, which shows a very balanced ratio between the p-type and then-type region. The p-type mobility is 0.43 cm²/Vs whereas the n-typemobility is 0.35 cm²/Vs. In comparison to the measurement disclosed inAdv. Mat. 2008, 2217-2224 the p-type mobility is improved by a factor of10 and for the same source-drain electrodes (Au) an almost equalperformance of the n-type behavior can be demonstrated.

Application Example 1c

Application example 1a is repeated, except that instead of the goldsource and drain electrodes silver contact electrodes are used (1c). Theresults are shown in the table below:

Bottom Bottom Example Gate Insulator Contacts μ_(h) [cm²/Vs] μ_(e)[cm²/Vs Reference¹⁾ Si SiO₂/OTS Au 0.05 ND 1b Si SiO₂/OTS Au 0.43 0.351c Si SiO₂/OTS Ag 0.026 0.022 ¹⁾Adv. Mater. 2008; 20, 2217-2224 (table1, type A)

Example 2

The starting material 4 is prepared according to example 2a ofWO2008000664 using decyl-tetradecyl-iodide. 2.0 g of 4, 0.59 g of2,5-thiopheneboronic acid bis(pinacol) ester, 24.4 mg oftri-tert-butylphosphonium tetrafluoroborate ((t-Bu)₃P*HBF₄), 48.6 mg oftris(dibenzylideneacetone) dipalladium (0) (Pd₂(dba)₃) in 50 ml oftetrahydrofuran and 1.13 g of potassium phosphate (K₃PO₄) dissolved in10 ml of water (previously degassed) is used. After 2 hours of reflux 24mg bromo-thiophene and 20 minutes later 31 mg thiophene-boronic acidpinacol ester is added to stop the polymerisation reaction. The reactionmixture is cooled to room temperature and precipitated in methanol. Theresidue is purified by soxhlet extraction using pentane and the polymeris then extracted with cyclohexane to give 1.67 g of a dark powder.Mw=43,300, Polydispersity=1.9 (measured by HT-GPC).

Application Example 2: DPP-Polymer 5 Based Organic Field EffectTransistors

Bottom-gate thin film transistor (TFT) structures with p-Si gate (10 cm)are used for all experiments. A high-quality thermal SiO₂ layer of 300nm thickness served as gate-insulator of C_(i)=32.6 nF/cm² capacitanceper unit area. Source and drain electrodes are patterned byphotolithography directly on the gate-oxide. Gold source drainelectrodes defining channels of width W=10 mm and varying lengths L=4,8, 15, 30 μm are used. Prior to deposition of the organic semiconductorthe SiO₂ surface is derivatized either with hexadimethylsilazane (HMDS)by exposing to a saturated silane vapour at 160° C. for 2 hours ortreating the substrate at 60° C. with a 0.1 m solution ofoctadecyltrichlorosilane (OTS) in toluene for 20 minutes. After rinsingwith iso-propanol the substrates are dried.

Transistor Performance in Toluene

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 5 obtained in example 2 in a0.5% (w/w) solution in toluene. The spin coating is accomplished at aspinning speed of 6000 rpm (rounds per minute) for about 10 seconds inambient conditions. The devices are dried at 100° C. for 15 minutesbefore evaluation.

The transistor behaviour is measured on an automated transistor prober(TP-10). From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 2.8×10⁻² cm²/Vs with anon/off current ratio of 4.7×10⁵ can be determined. The threshold voltageis at 5.6 V.

Transistor Performance in Chloroform

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 5 obtained in example 2 in a0.5% (w/w) solution in chloroform. The spin coating is accomplished at aspinning speed of 3000 rpm (rounds per minute) for about 20 seconds inambient conditions. The devices are evaluated after deposition.

The transistor behaviour is measured on an automated transistor prober(TP-10). From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 1.0×10⁻² cm²/Vs with anon/off current ratio of 3.3×10⁴ can be determined. The threshold voltageis at 5.4 V.

Example 3

7.1 g of 4, 2.62 g of 2,2′-bithiophene-5,5′-diboronic acid bis(pinacol)ester, 86.2 mg of tri-tert-butylphosphonium tetrafluoroborate((t-Bu)₃P*HBF₄), 172.3 mg of tris(dibenzylideneacetone) dipalladium (0)(Pd₂(dba)₃), 140 ml of tetrahydrofuran and 3.99 g of potassium phosphate(K₃PO₄) dissolved in 28 ml of water (previously degassed) is used. After2 hours of reflux 94 mg bromo-thiophene and 20 minutes later 110 mgthiophene-boronic acid pinacol ester are added to stop thepolymerisation reaction. The reaction mixture is cooled to roomtemperature and precipitated in methanol. The residue is purified bysoxhlet extraction using THF and the polymer is then extracted withchloroform to give 5.34 g of a dark powder. Mw=54,500,Polydispersity=1.7 (measured by HT-GPC).

Application Example 3

Bottom-gate thin film transistor (TFT) structures with p-Si gate (10 cm)are used for all experiments. A high-quality thermal SiO₂ layer of 300nm thickness served as gate-insulator of C_(i)=32.6 nF/cm² capacitanceper unit area. Source and drain electrodes are patterned byphotolithography directly on the gate-oxide. Gold source drainelectrodes defining channels of width W=10 mm and varying lengths L=4,8, 15, 30 μm are used. Prior to deposition of the organic semiconductorthe SiO₂ surface is derivatized either with hexadimethylsilazane (HMDS)by exposing to a saturated silane vapour at 160° C. for 2 hours ortreating the substrate at 60° C. with a 0.1 m solution ofoctadecyltrichlorosilane (OTS) in toluene for 20 minutes. After rinsingwith iso-propanol the substrates are dried.

Transistor Performance in Xylene

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 7 obtained in example 3 in a1% (w/w) solution in xylene. Before use the solution is filtered through0.2 m filter. The spin coating is accomplished at a spinning speed of800 rpm (rounds per minute) for about 20 seconds in ambient conditions.The devices are dried at 80° C. for 1 hour before evaluation.

The transistor behaviour is measured on an automated transistor prober(TP-10).

From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 2.5×10⁻¹ cm²/Vs with anon/off current ratio of 8.9×10⁸ can be determined. The threshold voltageis at 0.5 V.

Transistor Performance in Chloroform

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 7 obtained in example 1 in a0.5% (w/w) solution in chloroform. The spin coating is accomplished at aspinning speed of 3000 rpm (rounds per minute) for about 20 seconds inambient conditions. The devices are dried at 100° C. for 15 minutesbefore evaluation.

The transistor behaviour is measured on an automated transistor prober(TP-10).

From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 3.0×10⁻¹ cm²/Vs with anon/off current ratio of 9.3×10⁶ can be determined. The threshold voltageis at 0.8 V.

Example 4

1.0 g of 4, 148 mg of 2,5-thiopheneboronic acid bis(pinacol) ester, 185mg 2,2′-bithiophene-5,5′-diboronic acid bis(pinacol) ester, 12.2 mg oftri-tert-butylphosphonium tetrafluoroborate ((t-Bu)₃P*HBF₄), 24.3 mg oftris(dibenzylideneacetone) dipalladium (0) (Pd₂(dba)₃), 25 ml oftetrahydrofuran and 0.56 g of potassium phosphate (K₃PO₄) dissolved in 5ml of water (previously degassed) is used. After 2 hours of reflux 12 mgbromo-thiophene and 20 minutes later 16 mg thiophene-boronic acidpinacol ester is added to stop the polymerisation reaction. The reactionmixture is cooled to room temperature and precipitated in methanol. Theresidue is purified by soxhlet extraction using pentane and the polymeris then extracted with cyclohexane to give 0.83 g of a dark powder.Mw=51,500, Polydispersity=2.0 (measured by HT-GPC).

Application Example 4: DPP-Polymer 8 Based Organic Field EffectTransistors

Bottom-gate thin film transistor (TFT) structures with p-Si gate (10 cm)are used for all experiments. A high-quality thermal SiO₂ layer of 300nm thickness served as gate-insulator of C_(i)=32.6 nF/cm² capacitanceper unit area. Source and drain electrodes are patterned byphotolithography directly on the gate-oxide. Gold source drainelectrodes defining channels of width W=10 mm and varying lengths L=4,8, 15, 30 m are used. Prior to deposition of the organic semiconductorthe SiO₂ surface is derivatized either with hexadimethylsilazane (HMDS)by exposing to a saturated silane vapour at 160° C. for 2 hours ortreating the substrate at 60° C. with a 0.1 m solution ofoctadecyltrichlorosilane (OTS) in toluene for 20 minutes. After rinsingwith iso-propanol the substrates are dried.

Transistor Performance in Toluene

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 8 obtained in example 4 in a0.5% (w/w) solution in toluene. The spin coating is accomplished at aspinning speed of 6000 rpm (rounds per minute) for about 10 seconds inambient conditions. The devices are dried at 130° C. for 15 minutesbefore evaluation.

The transistor behaviour is measured on an automated transistor prober(TP-10).

From a linear fit to the square root of the saturated transfercharacteristics a field effect mobility of 2.1×10⁻¹ cm²/Vs with anon/off current ratio of 1.9×10⁷ can be determined. The threshold voltageis at 0.4 V.

Example 5

a) 228.06 g of 2-decyl-1-tetradecanol are mixed with 484.51 g 47%hydroiodic acid and the mixture is refluxed overnight. The product isextracted with t-butyl-methylether. Then the organic phase is dried andconcentrated. The product is purified over a silica gel column to give211.54 g of the desired compound 9 (73%). ¹H-NMR data (ppm, CDCl₃): 3.262H d, 1.26-1.12 41H m, 0.88 6H t;

b) A mixture of 30 mg FeCl₃, 10.27 g sodium and 600 mL t-amylalcohol isheated to 110° C. for 30 minutes before a mixture of 30.52 g of thenitrile and 24.83 g di-tert-amylsuccinate is added dropwise. Thereaction mixture is stirred at 110° C. over night before it is pouredonto water-methanol mixture. Büchner filtration and exhaustive washingwith methanol affords 33.60 g of the desired compound 10 as dark bluepowder with 90% yield. MS m/z: 464;

c) 33.55 g of the compound 10 are reacted with 12.22 g K₂CO₃ and 74.4 g2-decyl-1-tetradecyl iodide 9 in 1300 ml DMF at 110° C. overnight. Thereaction mixture is poured on ice and extracted with methylene chloride.Purification is achieved by column chromatography over silica gel andaffords 35.1 g of the desired compound 11 (42.7%). ¹H-NMR data (ppm,CDCl₃): 8.91 2H d, 7.35-7.32 6H m, 7.09 2H dxd, 4.05 4H d, 1.98 2H m,1.35-1.20 80H m, 0.89 6H t, 0.87 6H t;

d) 10.00 g of 11 and one drop of perchloric acid are dissolved in 200 mlof chloroform, cooled down to 0° C. and 2 equivalents ofN-bromosuccinimide are then added portion wise over a period of 1 h.After the reaction is completed, the mixture is washed with water. Theorganic phase is extracted, dried and concentrated. The compound is thenpurified over a silica gel column to give 5.31 g of a dark violet powderof the formula 12 (47%). ¹H-NMR data (ppm, CDCl₃): 8.85 2H d, 7.22 2H d,7.03 4H dxd, 4.00 4H d, 1.93 2H m, 1.29-1.21 80H m, 0.87 6H t, 0.85 6Ht.

e) 300 mg of compound 12, 78 mg thiophene-di-boronic acid pinacol ester,5 mg Pd₂(dba)₃ (tris(dibenzylideneacetone)-di-palladium) and 3 mgtri-tert-butyl-phosphonium-tetrafluoroborate are dissolved in 3 ml oftetrahydrofurane. This solution is degassed with 3 cycles offreeze/pump/thaw (Ar). The reaction mixture is then heated to refluxtemperature. Then 149 mg of K₃PO₄ are dissolved in 0.7 ml of water anddegassed under argon. The water solution is added to the THF solutionand the reaction mixture is refluxed over night. Then 5 mg of2-thiophene-mono-boronic-acid-pinacol-ester are added, and the mixtureis refluxed for another 30 minutes. Then 4 mg of 2-bromo-thiophene areadded, and the mixture is refluxed for another 30 minutes. The reactionmixture is cooled to room temperature and diluted with water and thenextracted with chloroform. The chloroform solution is then refluxed witha solution of NaCN in water for 1 hour. The water is separated and thechloroform solution dried. The residue is then Soxhlet extracted withtetrahydrofuran. The organic phase is evaporated to give 224 mg of thedesired polymer 13.

Example 6

To a mixture of 1.006 g of 4, 0.349 g of2,5-thieno[3,2-b]thiophenediboronic acid bis(pinacol) ester (e.g. madeby esterification of the corresponding diboronic acid (J. Org. Chem.,1978, 43(11), p 2199) with pinacol in refluxing toluene), 13 mg oftri-tert-butylphosphonium tetrafluoroborate ((t-Bu)₃P*HBF₄), 21 mg oftris(dibenzylideneacetone) dipalladium (0) (Pd₂(dba)₃) in 20 ml oftetrahydrofuran (degassed under Ar), a solution of 0.572 g of potassiumphosphate (K₃PO₄) dissolved in 1.7 ml of water (previously degassed) isadded. After 2 hours of reflux 4 mg bromo-thiophene and 20 minutes later5 mg thiophene-boronic acid pinacol ester is added to stop thepolymerization reaction. The reaction mixture is cooled down and dilutedwith chloroform. Then water is added. The layers are separated and theorganic layer is washed once more with water. The organic layer is thenconcentrated under reduced pressure. The chloroform solution is thenrefluxed over night together with a 1% NaCN solution in water. Thelayers are separated, the organic layer is then washed once more withwater and concentrated under reduced pressure. The crude product isprecipitated by the addition of methanol and filtered. The product isthen isolated by soxhlet extraction. A first fraction extracted withtetrahydrofurane is discarded, and the second fraction extracted withchloroform is precipitated by the addition of methanol to give 76 mg ofthe desired polymer of formula A as dark powder, Mw=25,800,polydispersity=2.0 (measured by HT-GPC).

Example 7

In a schlenk tube, a solution of 1.13 g of Ni(COD)₂ and 0.65 gbipyridine in 90 ml of toluene is degassed for 15 min. 3 g of thecorresponding dibrominated monomer 1 is added to this solution and thenthe mixture is heated to 80° C. and stirred vigorously overnight. Thesolution is poured on 500 ml of a 3/1/1 methanol/HCl (4N)/acetonemixture and stirred for 1 h. The precipitate is then filtrated,dissolved in CHCl₃ and stirred vigorously at 60° C. with an aqueoussolution of ethylenediaminetetraacetic acid (EDTA) tetrasodium salt forone additional hour. The organic phase is washed with water,concentrated and precipitated in methanol. The residue is purified bysoxhlet extraction using methanol, diethylether, cyclohexane and thepolymer is then extracted with CHCl₃ to give 1.7 g of a dark powder.Mw=37,000, Polydispersity=2.3 (measured by HT-GPC).

Application Example 5

Bottom-gate thin film transistor (TFT) structures with p-Si gate (10 cm)are used for all experiments. A high-quality thermal SiO₂ layer of 300nm thickness served as gate-insulator of C_(i)=32.6 nF/cm² capacitanceper unit area. Source and drain electrodes are patterned byphotolithography directly on the gate-oxide. Gold source drainelectrodes defining channels of width W=10 mm and varying lengths L=4,8, 15, 30 μm are used. Prior to deposition of the organic semiconductorthe SiO₂ surface is derivatized either with hexadimethylsilazane (HMDS)by exposing to a saturated silane vapour at 160° C. for 2 hours, by spincoating the HMDS at a spinning speed of 800 rpm (rounds per minute) forabout a minute or by treating the substrate at 60° C. with a 0.1 Msolution of octadecyltrichlorosilane (OTS) in toluene for 20 minutes.After rinsing with iso-propanol the substrates are dried.

Transistor Performance in Chloroform

The semiconductor thin film is prepared either by spin-coating or dropcasting the DPP derivative of the formula 15 obtained in example 7 in a0.5% (w/w) solution in chloroform. The spin coating is accomplished at aspinning speed of 3000 rpm (rounds per minute) for about 20 seconds inambient conditions. The devices are evaluated as deposited as well asafter drying at 120° C. for 15 minutes.

The transistor behaviour is measured on an automated transistor prober(TP-10). The DPP derivative of the formula 15 shows good ambipolarbehaviour in the standard device configuration.

Example 8

a) To a solution of 5.0 g Dithienyl-DPP (16) and 3.73 g2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxoborolane in 30 ml THF undernitrogen at −25° C. is added drop-wise a freshly prepared LDA solution(from 5.4 ml butyllithium 2.7 M and 2.2 ml diisopropylamin in 20 mlTHF,) over 15 minutes. The resulting reaction mixture is stirred for 1hour at 0° C. and then quenched with 100 ml 1 M HCl. The product isextracted with 2×50 ml TBME and the combined organic layers are washedtwice with brine and dried with sodium sulfate. After evaporation of thesolvent the residue is dissolved in 20 ml methylenchloride and thenslowly added to 200 ml of heavily stirred acetone. The precipitate iscollected by filtration, washed several times with acetone and dried at40° C. in a vacuum-oven, affording 6.3 g of pinkish-violet powder.¹H-NMR (ppm, CDCl₃): 8.90 2H, d, ³J=3.9 Hz; 7.71 2H, d, ³J=3.9 Hz; 4.054H d, ³J=7.7 Hz; 1.84 2H m; 1.37 24H m; 1.35-1.2 48, m; 0.9-0.8 12H m.

b) According to the procedure for the synthesis of polymer 3 describedin example 1, 0.91 g of 1 and 1.004 g of 17 are reacted to give polymer15. After the reaction, the mixture is poured into methanol and washedwith acetone, yielding in 1.2 g of polymer 15.

Example 9

According to the procedure for the synthesis of polymer 3 described inexample 1, 0.5 g of 17 and 0.12 g of dibromothiophene are reacted togive polymer 3. After the reaction, the mixture is poured into methanoland washed with acetone, yielding in 0.380 g of polymer 3. Mw=20,000,Polydispersity=2.3 (measured by HT-GPC).

Example 10

According to the procedure for the synthesis of polymer 3 described inexample 1, 0.5 g of 17 and 0.12 g of 2,5-dibromothiazole are reacted togive polymer 18. The residue is purified by soxhlet extraction usingpentane and the polymer is then extracted with cyclohexane to give 0.26g of a dark powder. Mw=17,700, Polydispersity=2.0 (measured by HT-GPC).

Example 11

According to the procedure for the synthesis of polymer 3 described inexample 1, 0.15 g of 17 and 0.05 g of 2,2′-Dibromo-[5,5′]bithiazolyl arereacted to give polymer 19. After the reaction, the mixture is pouredinto methanol and washed with acetone, yielding in 0.13 g of polymer 19.

Example 12

According to the procedure for the synthesis of polymer 3 described inexample 1, 2.3 g of 1 and 1 g 2,5-thieno[3,2-b]thiophenediboronic acidbis(pinacol) ester (e.g. made by esterification of the correspondingdiboronic acid (J. Org. Chem., 1978, 43(11), p 2199) with pinacol inrefluxing toluene) have been reacted to give polymer 20. After thereaction, the mixture was poured into methanol and washed with acetone,yielding in 2.0 g of polymer 20.

Example 13

a) A mixture of 5 mg iron trichloride (FeCl₃), 2.6 g of sodium and 100ml of t-amylalcohol is heated to 110° C. for 20 minutes before a mixtureof 5.0 g of the thiazole-2-nitrile of the formula 21 and 8.25 g ofdi-tert-amyl succinate of the formula 22 is added dropwise. The reactionmixture is stirred at 110° C. for 3 hours before it is poured onto 8.15g acetic acid in a water-methanol mixture (200 ml/100 ml). Büchnerfiltration and exhaustive washing with methanol affords 5.2 g of thedesired 1,4-diketopyrrolo[3,4-c]pyrrole (DPP) derivative of the formula23 as dark blue powder: ESI-MS m/z (% int.): 303.13 ([M+H]+, 100%).

b) A solution of 4 g of the 1,4-diketopyrrolo[3,4-c]pyrrole (DPP)derivative of the formula 3, 2.9 g of KOH in 3 ml of water and 18.5 g of1-bromo-2-hexyl-decyl in 50 ml of N-methyl-pyrrolidone (NMP) is heatedto 140° C. for 6 h. The mixture is washed with water and extracted withdichloromethane. Purification is achieved by column chromatography oversilica gel and precipitation out of chloroform/methanol which affords0.4 g of the desired DPP 24 as blue solid. ESI-MS m/z (% int.): 751.93([M+H]+, 100%). ¹H-NMR (ppm, CDCl₃): 8.05 2H, d, ³J=3.1 Hz; 7.70 2H, d,³J=3.1 Hz; 4.34 4H d, ³J=7.4 Hz; 1.86 2H m; 1.3-1.2 48, m; 0.9-0.8 12Ht.

c) Compound 25 is obtained in analogy to example 5d.

d) Polymer 26 is obtained in analogy to example 5e.

e) Polymer 27 is obtained in analogy to example 7.

Example 14

a) 554.6 g of potassium tert-butoxide, 424.2 g of dimethyl carbonate and3 L of anhydrous toluene are heated to 100° C. with stirring. 300 g of1-acetyl thiophene is added drop by drop during three hours and stirredat 100° C. for 15 hours. The reaction mixture is allowed to cool to roomtemperature and poured onto 4 L of ice. The water layer is separated andtwo times extracted with 200 ml of ethyl acetate. The organic layers arecombined and dried over sodium sulfate, filtered, evaporated and dried,giving 363.7 g of 28. The crude product is used for the next reactionstep without further purification.

b) 363.7 g of 28, 322.7 g of methyl bromooacetate, 288.7 g potassiumcarbonate, 1100 ml of acetone and 750 ml of 1,2-dimethoxyethane areplaced in a vessel. The mixture is stirred at 80° C. for 20 hours. Afterthe mixture has cooled down to room temperature, it is filtered anddried. 460 g of 29 are obtained. The crude product is used for the nextreaction step without further purification.

c) 218 g of 29, 643 g of ammonium acetate and 680 ml of acetic acid arestirred at 115° C. for 3 hours. After the reaction mixture has cooleddown to room temperature, it is poured into 3 L of acetone. The producedsolid is separated and washed with methanol and dried. 99.6 g of 30 areobtained.

d) A mixture of 5 mg iron trichloride (FeCl₃), 2 g of sodium and 40 mlof t-amylalcohol is heated to 110° C. for 20 minutes before a mixture of3.9 g of the thiazole-2-nitrile of the formula 21 and 7.82 g of 30 isadded portionwise. The reaction mixture is stirred at 110° C. for 3hours before it is poured onto 6.3 g acetic acid in a water-methanolmixture (100 ml/100 ml). Büchner filtration and exhaustive washing withmethanol affords 4.5 g of the desired 1,4-diketopyrrolo[3,4-c]pyrrole(DPP) derivative of the formula 31 as dark blue powder; ESI-MS m/z (%int.): 302.15 ([M+H]+, 100%).

e) Compound 32 is obtained in analogy to example 5c.

f) Compound 33 is obtained in analogy to example 5d.

g) Polymer 34 is obtained in analogy to example 5e.

h) Polymer 35 is obtained in analogy to example 7.

Example 15

Polymer 36 is obtained from compound 12 in analogy to example 7.

Example 16

a) In a three neck-flask, 83.6 g of potassium phosphate (K₃PO₄)dissolved in 110 ml of water (previously degassed) is added to adegassed solution of 20 g of thienylboronic acid, 22.0 g of2-bromothiazole, 2.3 g of tri-tert-butylphosphonium tetrafluoroborate((t-Bu)₃P*HBF₄) and 3.6 g of tris(dibenzylideneacetone) dipalladium (0)(Pd₂(dba)₃) in 350 ml of tetrahydrofuran. The reaction mixture is heatedat reflux temperature overnight. The reaction mixture is cooled to roomtemperature and 100 ml water was added. The reaction mixture wasextracted with ethylacetate and the organic layer was dried andevaporated under reduced pressure. It was further purified with columnchromatography using a gradient of hexane/ehtylacetate on silicagel. 8.0g of 2-thiophen-2-yl-thiazole 37 was obtained, spectral data correspondto the ones described in literature using Negishi-cross couplingreaction. (J. Jensen et al., Synthesis, 2001, 1, 128).

b) Compound 38 is obtained using the procedure known in literature (P.Chauvin et al., Bull. Soc. Chim. Fr. 1974, 9-10, 2099).

c) Compound 39 is obtained in analogy to the procedure known inliterature (A. D. Borthwick et al.; J. Chem. Soc., Perkin Trans 1, 1973;2769).

d) Compound 40 is obtained in analogy to example 5b.

e) Compound 41 is obtained in analogy to example 5c.

f) Compound 42 is obtained in analogy to example 5d.

g) Polymer 43 is obtained in analogy to example 5e.

h) Polymer 44 is obtained in analogy to example 7.

The polymers of the present invention can show higher field-effectmobility as the polymers disclosed in WO08/000664.

The invention claimed is:
 1. A copolymer of formula (VII)

wherein A is a group of formula

COM¹ is a group of formula

a is 2, n is number which results in a molecular weight of 10,000 to1,000,000 Daltons, Ar¹ and Ar^(1′) are a group of formula

Ar² is a group of formula

 and R¹ and R² are the same or different and are selected from abranched C₈-C₃₆alkyl group.
 2. The copolymer according to claim 1,wherein R¹ and R² are a branched C₁₂-C₂₄alkyl group.
 3. The copolymeraccording to claim 1, which has a weight average molecular weight of10,000 to 100,000 Daltons.
 4. A semiconductor device comprising thecopolymer according to claim
 1. 5. The semiconductor device according toclaim 4 is an organic field effect transistor.
 6. A process forpreparing an organic semiconductor device, the process comprising:applying a solution and/or dispersion comprising the copolymer accordingto claim 1 in an organic solvent to a substrate; and removing thesolvent.
 7. An integrated circuit comprising the organic field effecttransistor according to claim
 6. 8. A process for preparing thecopolymer of claim 1 comprising: reacting a dihalogenide X¹⁰-A-X¹⁰ withan equimolar amount of a diboronic acid or diboronate corresponding toformula

 or reacting a dihalogenide of formula

 with an equimolar amount of a diboronic acid or diboronatecorresponding to formula X¹¹-A-X¹¹, wherein X¹⁰ is halogen, and X¹¹ isindependently in each occurrence —B(OH)₂, —B(OY¹)₂,

 —BF₃Na, —BF₃N(Y¹⁵)₄, or BF₃K, wherein Y¹ is independently in eachoccurrence a C₁-C₁₀alkyl group and Y² is independently in eachoccurrence a C₂-C₁₀alkylene group, Y¹³ and Y¹⁴ are independently of eachother hydrogen, or a C₁-C₁₀alkyl group, Y¹⁵ is H, or a C₁-C₂₅alkylgroup, which may optionally be interrupted by —O—, in a solvent and inthe presence of a catalyst; or reacting a dihalogenide of formulaX¹⁰-A-X¹⁰ with an equimolar amount of an organo tin compoundcorresponding to formula

 or reacting a dihalogenide of formula

 with an equimolar amount of an organo tin compound corresponding toformula X^(11′)-A-X^(11′), wherein X^(11′) is independently in eachoccurrence —SnR²⁰⁷R²⁰⁸R²⁰⁹, wherein R²⁰⁷, R²⁰⁸ and R²⁰⁹ are identical ordifferent and are H or C₁-C₆alkyl, or two of the groups R²⁰⁷, R²⁰⁸ andR²⁰⁹ form a ring and these groups are optionally branched.
 9. Theprocess according to claim 8, wherein X¹⁰ is Br.
 10. The copolymeraccording to claim 1, wherein R¹ and R² are the same or different andare selected from 2-hexyldecyl and decyl-tetradecyl.
 11. The copolymeraccording to claim 3, having a weight average molecular weight of 20,000to 60,000 Daltons.